David,
I have experienced your Brinnibox sugestion with two primo microphones in o=
ne felmi preamplifier in roland r09, my question is, in you article you sai=
d the place where is the micro must be sealed, is it very inportant and why=
? You can see two pictures one the micro is not easy to see the other, is i=
nside the trunqued angle, the other is visible. And I have experienced with=
ou trunqued angle, the diference to me is not diferenciable.
Regards,
Jos=E9
--- In "Avocet" <> wrote:
>
> > Looks like a standard tripple boundary doubled / corner reflector
> > aka the pyramid:) - known art.
>
> Mike,
>
> I put the Brinibox forward as a _stereo project_ rather than a device.
> It isn't a "boundary effect" system but a double horn amplifier. Known
> technology yes, but what surprised me was that two simple pyramid
> horns used together gave a good stereo image. And what could be
> simpler in construction than two half boxes?
>
> The other good news is that anyone can cheaply try the idea out.
>
> My take on the PZM is that it is a miniature horn loading also using
> the surface and cosine effects. Doesn't look like a horn but
> acoustically that's what it is.
>
> I've read all sorts of articles, some of which seem to deny the
> existance of a "boundary effect". One article explained the use of
> three reflectors saying that each reflector contributed 6dBs making a
> total of 18dBs. Such an elementary boner put me off everything else in
> that article.
>
> As an ex pro film recordist, I do the experiment first and then work
> out why later. An early discovery was the extra directionality you get
> from placing a mic flat on a table. The theory behind this is the
> surface effect.
>
> With mics placed near a reflector, there are two distinct effects, the
> cosine effect due to the longitudinal polarisation of sound waves, and
> the surface effect which was once thought due to isothermal
> propagation near an object. I have a simpler explanation and want to
> experiment further when I get around to it. I think that thin
> "absorbent" materials which are too this to have an absorbent effect
> will alter the surface effect. I base this idea from using lapel mics
> under tablecloths for recording table conversations while filming.
> This amazed several of my assistants who didn't think it would work,
> but the others used the principle themselves as recordists.
>
> David
>
> David Brinicombe
> North Devon, UK
> Cogito cogito ergo cogito sum - Ambrose Bierce
>
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
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